One-way fares are usually half the price of the most expensive round-trip fares, which are valid for one year. The most restricted round-trip tickets are usually cheaper than the one-way tickets. Check both the one-way and the round-trip fare for your trip, even if you're only traveling one-way.

2. Sunday rule

One of the most common low fare restrictions is the requirement for your stay to incorporate at least one Sunday. For example, for a round-trip New York to Miami a passenger flying Tuesday to Thursday might pay USD 328, but a passenger whose stay includes a Sunday would pay much less - USD 188.

3. Advance purchasing

The least expensive fares often require advance purchasing - 7, 14, 21, days etc. before departure. You should keep in mind that seats for these cheapest fares are limited. The earlier you plan your trip the better your chances of getting a good fare.

4. Flight times

Airlines usually offer early morning and late evening flights - right before and after midnight when air traffic is light - at cheaper rates. If your time schedule allows, you might want to consider booking night flights to save money.

5. Are both legs of your trip with the same airline?

It is important to book the same airline for both legs of your trip. If you select different airlines for your outbound and return journeys you may not get any price showing at all. If you do get a price, it is likely to be significantly higher than the price you would get by booking with the same airline both ways. It depends whether the airlines have negotiated prices and agreements and whether they have any kind of mutual relations at all.

6. Check the restrictions

These tips and others can be found on the Air Fare Rules page, viewable when using the Fares method for booking. We highly recommend that you read these rules carefully before making your reservation.